The present invention relates to techniques for performing oilfield operations. More particularly, the present invention relates to techniques for performing fracture operations, such as stimulation, on a subterranean formation having at least one reservoir therein.
Oilfield operations are typically performed to locate and gather valuable downhole fluids. Typical oilfield operations may include, for example, surveying, drilling, wireline testing, completions, production, planning, and oilfield analysis. One such oilfield operation is a fracture operation used to facilitate production of fluids from a reservoir positioned in a subterranean formation. The fracture operation may involve, for example, fracturing, stimulation, seismic wave generation, measurement, testing and/or analysis. Fracturing typically involves the injection of a fracturing fluid into a subterranean formation to create or expand existing fractures in the reservoir.
In some cases, the fracturing fluid may contain proppants, such as sand grains, ceramic grains and/or other small particles, for creating a high conductivity drain in the formation. The fractures generated during a fracture operation may be simple fractures (e.g., bi-wing), or a complex networks of fractures that extend through the formation. These fractures create pathways between the reservoir and the wellbore to enable fluids to flow to the surface.
In performing fracture operations, it is often helpful to know certain fracture parameters, such as the hydraulic conductivity, the fracture width, fracture density, fracture porosity, local stress field, reservoir attenuation anisotropy, fracture velocities, the fluid pressure, the fracture length, fracture permeability, and/or the fracture conductivity. These fracture parameters may also include parameters of the reservoir, formation and/or other portions of the well site. Techniques have been developed to measure and/or map fractures as described, for example, in U.S. Pat. Nos. 7,134,492 and 2009/0166029. In some cases, seismic tools may be used to measure well site parameters. The use of downhole seismic techniques have been as described, for example, in PCT application PCT/GB2008/002271 and US Patent Application No. 2009/0168599.
Despite the advancements in fracture and seismic techniques, there remains a need to enhance fracture operations in subterranean formations and reservoirs contained therein. It is desirable that such techniques involve a more accurate determination of fracture parameters for simple and complex fractures. It is further desirable that such techniques consider the effects of stimulation of the subterranean formation and/or reservoir. Preferably, such techniques enable one or more of the following, among others: mapping simple and/or complex fracture networks, determining fracture parameters, stimulating the formation, providing images of the fracture(s), providing calibrations, monitoring and/or interpreting microseismic events.